English abstract
The Haradh and Karim formations at the Nimr High fields are poorly understood due to the limited well data drilled through the Karim Formation. This master’s thesis aims to enhance regional geological comprehension and evaluate the hydrocarbon exploration potential of the deep Karim and Haradh reservoirs within the Nimr High fields. Analysis was conducted, incorporating seismic interpretation, and integration of core and well-log data.
Seismic interpretation revealed that the Haradh surface features truncation in the northeast region of the Nimr High fields, while the Karim Formation illustrated a conformable surface. Haradh Formation has optimal reservoir properties; however, it is devoid of a cap rock. The Haradh surface has not produced structural characteristics conducive to significant hydrocarbon accumulation. Due to the limited wells in the Nimr High fields, a comparative analysis with the analog fields well data was considered to augment the interpretive accuracy. The thin sections, collected from analog fields (A) and (D), demonstrated that compaction is the dominant diagenetic process affecting the Khaleel reservoir. The density log in Well W1H1 reflects compaction at Nimr High fields. In addition, dolomite cement was observed, which reduced reservoir quality. Furthermore, the mineralogical chart also suggested the precipitation and cementation of chlorite, illite, clay, and kaolinite. Thin-section evaluation and prior studies indicated that secondary dissolution, if it occurs, will improve the reservoir quality. Core sample and well-log characterization signified the localized dissolution presence between adjacent fields. RMS amplitude and sweetness seismic attributes highlighted comparable anomalies in the analog-producing wells and the prospective hydrocarbon targets in Nimr High fields. The seismic interpretation identified that the prospects, A, B, C, D, E, and F exhibit similar acoustic impedance equivalent to those of the producing wells. This implied the potential existence of hydrocarbon and promising reservoir properties. The STOIIP findings and ranking of proposed hydrocarbon opportunities determined that prospects A and F are promising for drilling. Enhancing seismic resolution and acquiring additional thin sections at the Nimr High fields will provide a more detailed understanding of the reservoir.
